It's even more fundamental than human nature. Bikeshedding is better understood as an emergent behavior of groups of people than it is a thing that individuals do.

Bikeshedding-type comments come to dominate conversations because they take less time and effort to compose and express, and therefore tend to get in ahead of and (especially in a synchronous communication medium) crowd out more substantive contributions. While the expertise and temperament of the individual conversation participants may be contributing factors, the dominant one is simply the size of the group.